body {
  width: 100vw;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

#app {
  width: 400px;
  /* background-color: aqua; */
  box-sizing: border-box;
  padding: 20px;
  border: 1px solid #ccc;
}
